It is known that long-term relief from coronary artery disease and improved longevity may be achieved through complete revascularization of a patient who suffers from coronary artery stenosis or infarction of the myocardium. Revascularization by coronary artery bypass grafting (CABG) has long been the gold standard of total revascularization. In particular, a CABG procedure in which the left internal mammary artery (LIMA) is anastomosed to the left anterior descending (LAD) artery is well accepted as providing a superior survival rate. However, conventional CABG procedures have many drawbacks. Conventional CABG procedures require the patient to be placed on cardiopulmonary bypass (CPB) support, and typically require either a sternotomy or major thoracotomy to be employed. It is well known in the medical community that CPB produces many deleterious effects to the patient. A stemotomy is highly traumatic to the patient, requiring a lengthy recovery period and having some risk of life-threatening infection. As for a major thoracotomy, a patient typically endures much postoperative pain from such a procedure. Additionally, the use of Heparin, which is commonly prescribed for anticoagulation during a CABG procedure, carries its own potential risks and complications which are commonly known to surgeons. Furthermore, a CABG approach is often limited where the subject artery or arteries have multiple segmental or diffuse stenoses (e.g., the apex of the LAD), or where the arterial size is unacceptable for grafting.
Consequentially, advanced catheter-based therapies, and percutaneous transluminal coronary angioplasty (PTCA) in particular, have risen in popularity in order to provide less invasive means for treating coronary artery stenosis. These methods have the advantage of being less traumatic and require a shorter recovery time. However, they are not without their own limitations. It is known that PTCA carries a significantly higher restenosis and reintervention rates than a CABG procedure for the left anterior diagonal (LAD) artery, which provides the majority of blood flow to the left ventricle which is responsible for cardiac output to the vital organs. About 80-90% of patients suffering from symptomatic atherosclerosis require revascularization of the LAD. Accordingly, the use of catheter-based therapies alone to provide complete revascularization is limited in many cases.
Under certain conditions, operative transluminal coronary angioplasty (OTCA) has been used as an adjunct to CABG in the course of one operation. Most commonly, OTCA has been performed through the arteriotomy used for the grafting site, and then only in the context of standard CPB. Unfortunately, OTCA has not shown a proven record of long-term patency rates.
Considering all of the above, there is a need to for an improved method of revascularization which optimizes the individual advantages of CABG procedures and catheter-based interventions while eliminating some of the drawbacks of these procedures when performed independently of the other. Such a method would preferably involve a "hybrid" approach comprising a CABG procedure performed in conjunction with catheter-based interventions and/or diagnosis. The method would preferably eliminate some of the drawbacks of conventional CABG procedures and, in particular, would eliminate the need for CPB for the reasons discussed above. Applicant's copending U.S. patent application, entitled "Method for Coronary Artery Bypass" and having Ser. No. 08/419,991, discloses a method for performing "Minimally Invasive Direct Coronary Artery Bypass Grafting" (MIDCAB.TM.) on a beating heart, and is hereby incorporated by reference in its entirety.
The MIDCAB method involves a direct access or "direct vision" approach in which bypass grafting is accomplished through a small surgical "window" in the patient's chest. This window is preferably a minimal thoracotomy formed by an intercostal incision generally less than 12 cm. Access to the heart is provided by a retractor which spreads the ribs both horizontally and vertically. Other access ports through the thoracic cavity may be employed if necessary but are not required. The MIDCAB method includes techniques which eliminate the need for CPB while still providing a substantially bloodless and stable operating field for ensuring a successful anastomosis. Most advantageously, the portion of the heart proximate to the vessel to be bypassed is stabilized, and a segment of the vessel is occluded, preferably both proximally and distally to the arteriotomy site. This is accomplished by providing ligating stay sutures at the appropriate locations of the vessel or by other more sophisticated stabilization means which are discussed in more detail below. The method is primarily directed to grafting the LIMA to either the LAD, the diagonal (Dx) and circumflex (Cx) arteries; the latter grafts being typically accomplished by means of a "T-graft" with the radial artery from the LIMA sequentially to the Dx and Cx arteries.
Furthermore, the MIDCAB approach is far less traumatic and less painful than conventional approaches which require CPB and employ a stemotomy or a major thoracotomy. Additionally, the MIDCAB method has been shown to obviate the need for Heparin or require only minor doses.